Methods and apparatus for smoothing text outlines

ABSTRACT

Methods and apparatus are provided to smooth a jagged outline of a reconstructed text generated through any of a variety of systems, such as, for example, an image scanner. Given the reconstructed text with a jagged outline, the methods smooth the outline of the text first through location of horizontal and vertical edges, and subsequent gray scale reconstruction of the edge ink level from a one-bit or a low number of bits edge pattern. The methods then provide identification of the local text outline pattern and corresponding ink level adjustment of the center pixel. The methods produce text having very smooth horizontal and vertical edges. The methods then smooth slanted edges, mend holes in the text, and remove isolated pixels of ink.

REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. application Ser. No.09/721,404, filed Nov. 21, 2000, now U.S. Pat. No. ______, which is acontinuation-in-part of U.S. application Ser. No. 09/111,633, filed Jul.7, 1998, now U.S. Pat. No. 6,310,697.

FIELD OF THE INVENTION

[0002] The present invention relates to image text smoothing. Moreparticularly, the present invention relates to a method and apparatusfor producing text images with improved smoothness in horizontal,vertical, and slanted edges, and for hole mending and dot removal.

BACKGROUND OF THE INVENTION

[0003] Text or pictorial images are often replicated or transmitted by avariety of techniques, such as photocopying, facsimile transmission, andscanning images into a memory device. The process of replication ortransmission often tends to degrade the resulting image due to a varietyof factors. Degraded images are characterized by indistinct or shiftededges, blended or otherwise connected characters and distorted shapes.

[0004] A reproduced or transmitted image that is degraded in quality maybe unusable in certain applications. For example, if the reproduced ortransmitted image is to be used in conjunction with a characterrecognition apparatus, the indistinct edges, connected characters, etc.may preclude accurate or successful recognition of characters in theimage. Also, if the degraded image is printed or otherwise renderedvisible, the image may be more difficult to read and less pleasing tothe eye.

[0005] There are several approaches to improve image quality. Aclassical resolution enhancement algorithm for example, is templatematching. Template matching attempts to match a line, curve pattern, orlinear pattern and then tries to find the best way to reconstruct itwith the printing resolution. However, after an image has beenreconstructed using an enhancement technique, jagged outlines, holes,and undesired dots may still occur in the resulting reconstructed image.It is desirable to smooth these unwanted jagged outlines, and toeliminate unwanted holes and dots.

[0006] The prior art teaches smoothing techniques only for corners anddiagonals. Also, the prior art assumes one-bit input. The prior arttypically has been used within or in conjunction with resealingprocesses.

[0007] Yamashita et al. U.S. Pat. No. 5,559,530 (“Yamashita”) disclosesan image processing apparatus that comprises a font ROM for storingbinary font data, and that generates a font with contour lines expressedwith gradations. An output port is provided for reading a target pixelwith ambient pixels arranged in a 3×3 matrix of the binary font datastored in the font ROM. A shift register produces address data based onthe binary data read from the font ROM. A look-up table has 2^(3×3)elements in which multilevel values are commensurate with the pixelpatterns included in the 3×3 matrix. One datum of the multilevel data isoutput from the look-up table by designating one element by the addressdata, and is used as gradation data of the target pixel. Thus, the fontpixel can be expressed with a gradation and the jagged contour of thefont is reduced.

[0008] Yamashita assumes smoothing bit-map image data. That is,Yamashita teaches generating multilevel data values from bit-map imagedata values wherein the bit-map image data values correspond torespective pixels. Each of the pixels has a respective binary level andincludes four sub-areas, each of which correspond to a respectivesub-pixel. Also, Yamashita teaches a conversion table having 2^(3×3)elements, wherein each element includes a set of density data valuesthat are arranged in a 2×2 matrix and in a predetermined order. Thedensity data values are calculated from the percentage of the black areaof a sub-area of each of the sub-pixels, wherein the area is based onone or more main contour lines which is predicted from the positions ofblack pixels in the matrix-shaped area, and the sub-pixels, being 2×2sub-divisions of the pixel area of the target pixel.

[0009] Zeng European Patent Application EP 0 719 034 A1 (“Zeng”)discloses a scanner/printer system for smoothing the edges of text orline art. The system includes a copy board for an image bearing anoriginal, a CCD, a PCI bus, a processor which uses edge smooth softwareand a laser printer. The edge smooth software adds variable size fill-inpatterns of pixels to the image data scanned by the CCD at lowresolution to smooth the edges of text or line art prior to printing athigh resolution. Zeng teaches smoothing curves and diagonals, andsmoothing many different sizes of corners and chinks, and using one-bitprinting. Zeng requires orientation estimation for many differentangles.

[0010] It would be advantageous to provide methods and apparatus thatminimize the modification of data, that is, as faithfully to theoriginal input as possible.

[0011] It would be advantageous to provide methods and apparatus thatrecognize and handle outliers or degraded, jaggy or otherwise corruptoriginal data, especially with respect to vertical and horizontal edges.

[0012] It would be advantageous to provide methods and apparatus thatrecognize and handle outliers or degraded, jaggy, or otherwise corruptoriginal data from non-ideal source inputs, such as, for examplehalf-tone text edges or scanned text.

[0013] It would be advantageous to provide methods and apparatus thatare fast, simple, and flexible.

[0014] It would be advantageous to provide methods and apparatus thatprovide general enhancements comprising, for example, hole-filling,isolated dot removal, and anti-aliasing.

[0015] It would be advantageous to provide conversion tables that areorganized by jaggy levels with a preference for minimal change. That is,jaggy level zero dominates.

[0016] It would be advantageous to provide conversion tables thatprovide a final output ink level for a center pixel as a function of itsoriginal ink level, and as a function of the surrounding ink andbackground pattern. Such a table provides substantially different outputink from other tables for a particular ink and background pattern,depending on the original center ink level.

[0017] It would be advantageous to provide conversion tables that areorganized efficiently into distinct patterns using concepts of rotation,reflection, and complements.

SUMMARY OF THE INVENTION

[0018] Methods and apparatus are provided to smooth a jagged outline ofreconstructed text generated through any of a variety of systems, suchas, for example, an image scanner. Given the reconstructed text with ajagged outline, the methods smooth the outline of the text first throughlocation of horizontal and vertical edges, and subsequent gray scalereconstruction of the edge ink level from a one-bit or a low number ofbits edge pattern. The methods then provide identification of the localtext outline pattern and corresponding ink level adjustment of thecenter pixel. The methods produce text having very smooth horizontal andvertical edges. The methods then smooth slanted edges, mend holes in thetext, and remove isolated pixels of ink.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above-mentioned objects and features of the present inventioncan be more clearly understood from the following detailed descriptionconsidered in conjunction with the following drawings, in which the samereference numerals denote the same elements throughout, and in which:

[0020]FIG. 1 is a flow diagram of an application of a preferredembodiment of the invention;

[0021]FIG. 1a is a diagram of associated devices for FIG. 1;

[0022]FIG. 1b is a flow diagram of an application of a preferredembodiment of the invention;

[0023]FIG. 2 is a diagram of a text outline according to the invention;

[0024]FIG. 3 is a flow diagram of a method according to the invention;

[0025]FIG. 4 is a flow diagram of a first main procedure according tothe invention; and

[0026]FIG. 5 is a flow diagram of a second main procedure according tothe invention.

DETAILED DESCRIPTION OF THE INVENTION

[0027] Methods and apparatus are provided to smooth a jagged outline ofreconstructed text generated through any of a variety of systems, suchas, for example, an image scanner. Given the reconstructed text with ajagged outline, the methods smooth the outline of the text first throughlocation of horizontal and vertical edges, and subsequent gray scalereconstruction of the edge ink level from a one-bit or a low number ofbits edge pattern. The methods then provide identification of the localtext outline pattern and corresponding ink level adjustment of thecenter pixel. The methods produce text having very smooth horizontal andvertical edges. The methods then smooth slanted edges, mend holes in thetext, and remove isolated pixels of ink.

[0028] Smoothing Text Outlines

[0029] This invention may be used to smooth the jagged outline of textgenerated through text-enhancement methods. An exemplary textenhancement system is described below for the convenience of the reader.It should be appreciated that the claimed invention herein is by nomeans limited to using that text enhancement system. Furthermore, it isnoted that the invention can work with other text enhancement methods,or even without a text enhancement method. However, in either case, thetext in the claimed invention herein is required to have dark contouraround it.

[0030] The Text Enhancement System.

[0031] The text enhancement systems described herein comprise easy touse page processing systems that enhance text on a digitally scannedpage, thereby improve the crispness, clarity, and readability of thetext. In addition, text enhancement systems in accordance with thisinvention are independent of the type of scanner used and utilize an inkredistribution system that increases the contrast of digitally scannedtext or facsimiles.

[0032] A preferred embodiment of text enhancement systems in accordancewith this invention provides a general purpose method for textenhancement that is independent of the type of scanner that is used toscan a document or the device printing the document. It is tolerant ofthe artifacts and defects that the scanning process introduces on thetext, mainly blurring. The text enhancement system is ideal for imagereconstruction systems for scanned or digitized images that are notsynthetic, i.e., the image is not a result of any PostScript or PageDescription Language (“PDL”) processing.

[0033] Typically, a page is scanned and a digitized image is obtainedthat is usually in an RGB format. If no specific enhancement proceduresare applied to the text in the document, then the result is text that isnot crisp, clear, or sharp and is therefore harder to read and lesspleasant to the eyes.

[0034] Text enhancement systems in accordance with this inventionpreserve the amount of ink on the textual part of the page using aconsistent method. The text is reconstructed through the reallocation ofink. There is a correspondence between the original amount of ink on thedocument and the intensity of the ink that the scanner read. Thecorrespondence is either the same or there is some scaling factorinvolved. The factor is obtained by the fact that there is some overlapbetween two scanned pixels. The factor is also independent of thelocation of the pixels.

[0035] The new textual image is reconstructed where the same amount or afactor of the ink is preserved. Text has a centralization property. Theink is centralized, that is, there are rarely holes in groups of darkpixels. For example, there is a large white area surrounded by a blackarea in the letter “O” but it is not at the pixel level, it is at amulti-pixel level. If there are eight pixels that are black surroundingone pixel that is white, then it is likely that the white area is amisread by the scanner and there are actually nine pixels that areblack. The ink on the page is arranged so that it is more centralized,more connected to other pixels that are dark.

[0036] A window of size W×W is constructed on a scanned page with thetarget pixel at the center of the window. The amount of ink in thewindow is calculated and the number of pixels that are darker than thecenter pixel is counted. The window is moved along the page and eachpixel on the page has a chance to be the center of a window and beallocated ink. Text enhancement systems in accordance with thisinvention reallocate the amount of ink in full quantities of the darkestvalue. Only the center pixel will actually have its ink reallocated.

[0037] This reallocation is a key feature of the text enhancementsystems described herein. First, attempt to allocate the ink pixel bypixel in the window. The darkest pixel gets ink, the second darkest getsink, and so on, until there is no more ink remaining in the bank, wherethe initial amount of ink in the bank is equal to the total amount ofink in the window. If the center pixel is later in darkness and there isno ink left in the bank, then it will become white. If the center pixelis reached before the ink runs out, then it will become black. Only thereallocation to the center pixel becomes effective. The attempt toallocate ink to the other pixels in the window is only done to determinethe center pixel's allocation. Those pixels are reallocated ink whenthey become the center of a current window. Text enhancement systems inaccordance with this invention are not limited to black text on a whitebackground, but also apply to grayscale, color, and white text on ablack background.

[0038] For example, the amount of ink in a window is ten and the centerpixel is the third darkest in the window. This means that only two otherpixels in the window are darker than the center pixel. The textenhancement system cited herein reallocates the ink to the pixels. Giventhis example, it is desirable to have the center pixel black. If theamount of ink in the window were only three and the center pixel wassixth in darkness, then no ink would be put in the center pixel becausereallocating the amount of ink in the window would not leave any forthat pixel.

[0039] It is also noted that the claimed invention herein assumes theavailability of multiple-bit printing. It can be applied to other jaggedtext outlines that resemble, but are not limited to, one-bit or lownumber of bits text reconstruction.

[0040]FIG. 1 is a flow diagram of an application of a preferredembodiment of the invention. A text image is scanned into a scanner 1.The text image is enhanced by a Text Enhancement System 2, whichprovides the enhanced image as input into the claimed invention,Smoothing Text Outlines 3. Smoothing Text Outlines 3 then smoothes theoutlines of the text image according to the invention and provides theresulting image as input into a printer 4.

[0041]FIG. 1a is a diagram of associated devices for FIG. 1. FIG. 1ashows an embodiment of the claimed apparatus. The scanner 1 providesinput to a computing device 5, comprising the Text Enhancement System 2,and the claimed invention, Smoothing Text Outlines 3. That is, residingin computing device 5 are means for locating horizontal and verticaledges of text images, means for smoothing the horizontal and verticaledges, means for locating slanted edges of the text images, and meansfor smoothing the slanted edges. Computing device 5 thus provides theoutput of the Smoothing Text Outlines 3 as input to printer 4. Computingdevices can be, for example, stand-alone computers, image processingchips, and the like.

[0042]FIG. 1b is a flow diagram of an illustrative application of apreferred embodiment of the invention. A document is scanned into ascanner 11. The pages of the scanned image are enhanced 12. The text ofthe enhanced image is smoothed according to the preferred embodiment ofthe invention 13. The smoothed image is faxed 14 to a desireddestination and received 15 at the destination. It is appreciated thatthe claimed invention is not limited to scanner, printer, and faxdevices, but can be used with a variety of utility devices.

[0043]FIG. 2 is a diagram of a text outline 10 of a typical text image,letter C 20 according to the invention. Given a reconstructed text withjagged outline, the preferred embodiment smoothes the outline of thetext through two main separate procedures, as depicted in FIG. 3. Thesmoothing method starts 30 and invokes the first main procedure,identifying the precise location of horizontal and vertical edges andperforming subsequent gray-scale reconstruction of the edge ink-levelfrom an edge pattern 31. It is noted that the eye is more sensitive totext outline jaggedness in both the horizontal and vertical direction.The second procedure, identifying the local text outline pattern andcorresponding ink-level adjustment of the center pixel 32, issubsequently invoked. Then the method ends 33.

[0044] Step 31 produces text with smooth horizontal and vertical edges.Step 32 smoothes slanted edges, i.e. similar to anti-aliasing, and alsohelps to mend holes in the text and remove isolated pixels of ink.

[0045] Horizontal and Vertical Edge Smoothing

[0046] In the preferred embodiment, at each pixel around a text outlinewe look at a 3×N neighborhood for horizontal edge detection and an N×3neighborhood for vertical edge detection of the pixel. The TextEnhancement System cited herein identifies the text outline through atag in the output. N is chosen to be seven (7). Other values for N canbe used, but N=7 is chosen for the following reasons. First, N is chosento be odd for obtaining symmetry. Then, if N is too small, it is lesslikely to be able to detect vertical and horizontal edges. If N is toolarge, then computation is increased unnecessarily because little or noimproved performance is gained. N=5 is another value that can be used,but N=7 is found to be more robust. A threshold ink-level, T_(dark) ischosen such that any pixel darker than T_(dark) is considered part ofthe text while the rest of the pixels are consider part of thebackground. The precise value of T_(dark) is not very critical becauseit is assumed that the original text has sharp jagged outlines so thatink pixels and background pixels are easily distinguished.

[0047] According to the preferred embodiment, a horizontal edge isidentified by the following condition. In a 3×N window, if the first rowcontains at least N−n ink pixels and the last row at least N−nbackground pixels or vice versa, where n is the number of outliersallowed, then the middle row is detected as the precise edge location,subject to the further condition that the outlying pixels cannot bedirectly above or below the center of the window. That is, outliers onthe central column of the window are not permitted. In the preferredembodiment, N=7 and n=1. A vertical edge is identified similarly byusing an N×3 window and by counting ink and background pixels in columnsinstead of in rows.

[0048] Once a horizontal or a vertical edge is detected, the ink valueof the center pixel in the window is replaced by a convenient average ofthe ink values on the edge. As an example of finding such a convenientaverage of ink values on a horizontal edge, the ink values of ink pixelsdarker than T_(dark) in the middle row are summed and the sum is dividedby N. Other averaging techniques can be used.

[0049] Following is an example of a preferred embodiment of theinvention, wherein T_(dark)=175, and 8-bit printing is assumed. Table Aherein below is a 3×7 window of ink and background pixels that is inputto the herein claimed invention. The ink pixels and the backgroundpixels are subsequently binarized. That is, each pixel is identified aszero (0) to denote it is a background pixel or as one (1) to denote itis an ink pixel, using T_(dark) as the threshold criteria to distinguishbetween ink and background pixels. Table B herein below depicts therespective ink and background binary values for the pixels in Table A.TABLE A 230 240 34 192 199 222 210 71 201 54 44 223 231 20 34 45 55 21220 17 33

[0050] TABLE B 1 1 0 1 1 1 1 0 1 0 0 1 1 0 0 0 0 0 1 0 0

[0051] Table B shows that the top row is identified as dark because ithas six (6), or greater than or equal to N−n ink pixels, and wherein thesingle outlying pixel (the third pixel) is not located in the centralcolumn. Table B shows that the bottom row as light. The middle row istherefore identified as a horizontal edge and the ink value of thecenter pixel of the window is replaced by:

(201+223+231)/7=93.

[0052] Slanted Edge Smoothing and Hole Mending/Dot Removal

[0053] In the preferred embodiment, each pixel has a 3×3 neighborhoodthat is considered. The region is binarized into ink and backgroundpixels using the threshold T_(dark). For each pattern of nine (9) ink orbackground pixels in the window, a smoothing level is assigned withvalues ranging from zero (0) to three (3). The ink value of the centerpixel is then modified in accordance to this smoothing level, which isalso described in Table C herein below. TABLE C Class of Center PixelInk Background Smoothing Level 0 no change no change 1 reduce ink by255-ink increase ink by half of 255- ink 2 reduce ink by twice of 255-increase ink by ⅔ of 255- ink ink 3 replace ink by 15 replace ink by 235

[0054] The distinct ink and background patterns in the preferredembodiment and their corresponding smoothing levels, herein alsoreferred to as jaggy levels, are given in Table D herein below. Patternsthat are related to one another through a rotation or a reflection areassigned the same smoothing level. Only one of them is listed hereinbelow in Table D. Furthermore, this list in Table D only shows thosecases wherein the center pixel is an ink pixel. The smoothing level ofthe center pixel when it is a background pixel can be deduced from thebinary complement of the list given in Table D. TABLE D (0 = background,1 = ink) Level 0 111 111 111 111 111 111 111 111 110 111 111 111 111 011111 011 011 011 010 111 111 011 010 011 111 111 011 011 101 110 111 010011 100 110 010 110 011 111 110 110 110 111 110 110 101 011 010 011 011010 011 011 111 010 010 011 011 011 011 011 011 101 101 110 010 100 110100 100 100 110 011 111 011 110 010 000 000 001 000 001 001 001 010 010011 011 111 110 111 110 111 110 110 010 110 010 010 001 010 011 001 100010 010 001 101 000 000 000 001 110 110 111 010 010 001 000 100 Level 1111 111 101 000 000 000 000 011 011 010 110 110 010 110 001 000 101 110101 100 100 Level 2 100 000 000 110 110 010 100 000 101 Level 3 000 010000

[0055]FIG. 4 is a flow diagram of a first main procedure 31 thatperforms horizontal and vertical edge smoothing on a pixel from a textenhancement system according to the preferred embodiment of theinvention. The method centers a 3×7 window and a 7×3 window on a currentpixel 401. The method then determines if the current pixel is a textenhanced or a neighbor to a text enhanced pixel 402. If it is not, thenthe method goes to the next pixel 403.

[0056] If the current pixel is a text enhanced or a neighbor to a textenhanced pixel, then the method examines the top or bottom row of the3×7 window and determines if there is at most one dark pixel exceedingT_(dark), wherein the dark pixel is not the middle pixel 404. If thereis at most one dark pixel, wherein the dark pixel is not the middlepixel, then the method examines the other top or bottom row of the 3×7window and determines if there is at most one light pixel less thanT_(dark), wherein the light pixel is not the middle pixel 405. If thereis at most one light pixel, wherein the light pixel is not the middlepixel, the method then sets the ink value of the current pixel to anaverage of the ink values of the middle row 406. The method then goes tothe next pixel 407.

[0057] If there is not at most one light pixel, wherein the light pixelis not the middle pixel, or if there is not at most one dark pixel,wherein the dark pixel is not the middle pixel, then the method examinesthe right or left column of the 7×3 window and determines if there is atmost one dark pixel, wherein the dark pixel is not the middle pixel 408.If there is at most one dark pixel, wherein the dark pixel is not themiddle pixel, then the method examines the other right or left column ofthe 7×3 window and determines if there is at most one light pixel,wherein the light pixel is not the middle pixel 409. If there is at mostone light pixel, wherein the light pixel is not the middle pixel, themethod sets the ink value of the current pixel to an average of the inkvalues of the middle column 410 and goes to the next pixel 407.

[0058] If there is not at most one dark pixel, wherein the dark pixel isnot the middle pixel 408, or if there is not at most one light pixel,wherein the light pixel is not the middle pixel 409, the method goes onto a second main procedure that performs slanted edge smoothing, andhole mending and dot removal 411 described herein below.

[0059]FIG. 5 is a flow diagram of a second main procedure 32 thatperforms slanted edge smoothing, and hole mending and dot removalaccording to the preferred embodiment of the invention. The methodcenters a 3×3 window at the current pixel 501. Then the method finds thepattern number of the light and dark pixels pattern in the 3×3 window502. The method then determines the jaggy level for the pattern from alook-up conversion table 503. The look-up conversion table's contentsare jaggy levels, which herein are zero (0), one (1), two (2), and three(3). It is noted that the look-up conversion table cited herein can becreated by empirical trial and error methods. The method then modifiesthe ink value of the current pixel according to the jaggy level 504. Themethod then ends 505.

[0060] Accordingly, although the invention has been described in detailwith reference to particular preferred embodiments, persons possessingordinary skill in the art to which this invention pertains willappreciate that various modifications and enhancements may be madewithout departing from the spirit and scope of the claims that follow.

We claim:
 1. A method for smoothing a jagged outline of a text image,the method comprising: locating horizontal and vertical edges of thetext image; smoothing the horizontal and vertical edges; locatingslanted edges of the text image; and smoothing the slanted edges.
 2. Themethod of claim 1, wherein smoothing horizontal and vertical edgesfurther comprises providing gray scale reconstruction of each edge pixelink level of the horizontal and vertical edges using a multiple-bit edgepattern.
 3. The method of claim 1, wherein smoothing horizontal andvertical edges further comprises providing gray scale reconstruction ofeach edge pixel ink level of the horizontal and vertical edges using aone-bit edge pattern.
 4. The method of claim 1, wherein for each pixelof the slanted edge, locating slanted edges further comprisesidentifying a local text outline pattern of the pixel, and whereinsmoothing slanted edges further comprises identifying an ink leveladjustment value for the pixel.
 5. The method of claim 4, whereinsmoothing slanted edges further comprises mending holes and removingisolated pixels of ink.
 6. The method of claim 1, wherein the jaggedoutline of the text image is generated by a text enhancement system,such that each pixel around the jagged outline is identified by a taggiven by the text enhancement system output.
 7. The method of claim 1,wherein locating slanted edges further comprises, for each pixel of thejagged outline: centering a 3×3 window on the outline pixel; determiningfor each pixel of the 3×3 window if the window pixel is an ink pixel orpart of a background, wherein the ink pixel is part of the text image;identifying a pattern for the 3×3 window; assigning a smoothing levelassociated with the pattern; and replacing the ink value of the centeredoutline pixel by a processed ink value, the processed ink valueassociated with the smoothing level.
 8. The method of claim 7, whereindetermining if the window pixel is an ink pixel further compriseschoosing a threshold ink level value, such that if an ink value of thewindow pixel is greater than or equal to the threshold ink value, thenthe window pixel is an ink pixel, and if the ink value of the windowpixel is less than the threshold ink value, then the window pixel is abackground pixel.
 9. The method of claim 7, wherein patterns that arerelated to one another through a rotation or a reflection or acomplement are assigned the same smoothing level, thereby reducing thenumber of distinct patterns.
 10. Apparatus for smoothing a jaggedoutline of a text image, the apparatus comprising: means for locatinghorizontal and vertical edges of the text image; means for smoothing thehorizontal and vertical edges; means for locating slanted edges of thetext image; and means for smoothing the slanted edges.
 11. The apparatusof claim 10, wherein the means for smoothing horizontal and verticaledges further comprises means for providing gray scale reconstruction ofeach edge pixel ink level of the horizontal and vertical edges using amultiple-bit edge pattern.
 12. The apparatus of claim 11, wherein themeans for smoothing horizontal and vertical edges further comprisesmeans for providing gray scale reconstruction of each edge pixel inklevel of the horizontal and vertical edges using a one-bit edge pattern.13. The apparatus of claim 10, wherein for each pixel of the slantededge, the means for locating slanted edges further comprises means foridentifying a local text outline pattern of the pixel, and wherein themeans for smoothing slanted edges further comprises means foridentifying an ink level adjustment value for the pixel.
 14. Theapparatus of claim 13, wherein the means for smoothing slanted edgesalso mends holes and removes isolated pixels of ink.
 15. The apparatusof claim 10, wherein the jagged outline of the text image is generatedby a text enhancement system, such that each pixel around the jaggedoutline is identified by a tag given by the text enhancement systemoutput.
 16. The apparatus of claim 10, wherein the means for locatingslanted edges further comprises, for each pixel of the jagged outline:means for centering a 3×3 window on the outline pixel; means fordetermining for each pixel of the 3×3 window if the window pixel is anink pixel or part of a background, wherein the ink pixel is part of thetext image; means for identifying a pattern for the 3×3 window; meansfor assigning a smoothing level associated with the pattern; and meansfor replacing the ink value of the centered outline pixel by a processedink value, the processed ink value associated with the smoothing level.17. The apparatus of claim 16, wherein means for determining if thewindow pixel is an ink pixel further comprises means for choosing athreshold ink level value, such that if an ink value of the window pixelis greater than or equal to the threshold ink value, then the windowpixel is an ink pixel, and if the ink value of the window pixel is lessthan the threshold ink value, then the window pixel is a backgroundpixel.
 18. The apparatus of claim 16, wherein patterns that are relatedto one another through a rotation or a reflection or a complement areassigned a same smoothing level, thereby reducing a number of distinctpatterns.
 19. A method for determining and smoothing a slanted edge of ajagged outline of a text image, for each pixel of the jagged outline,the method comprising: centering a 3×3 window on the outline pixel;determining for each pixel of the 3×3 window if the window pixel is anink pixel or part of a background, wherein the ink pixel is part of thetext image; identifying a pattern for the 3×3 window; assigning asmoothing level associated with the pattern; and replacing the ink valueof the centered outline pixel by a processed ink value, the processedink value associated with the smoothing level.
 20. The method of claim19, wherein determining if the window pixel is an ink pixel furthercomprises choosing a threshold ink level value, such that if an inkvalue of the window pixel is greater than or equal to the threshold inkvalue, then the window pixel is an ink pixel, and if the ink value ofthe window pixel is less than the threshold ink value, then the windowpixel is a background pixel.
 21. The method of claim 19, whereinpatterns that are related to one another through a rotation or areflection or a complement are assigned a same smoothing level, therebyreducing a number of distinct patterns.
 22. The method of claim 19,further comprising mending holes and removing isolated pixels of ink.